TypeScript Constructor Overloading

TypeScript Classes and OOP : Exercise-6 with Solution

Write a TypeScript program that creates a class called Student with properties name and roll number. Add constructor overloading to support multiple ways of initializing a Student object. Implement one constructor that takes both name and roll number as parameters and another constructor that takes only name, assuming the roll number is unknown.

Sample Solution:

TypeScript Code:

class Student {
  // Properties
  name: string;
  rollNumber: number | undefined;

  // Constructor with both name and roll number
  constructor(name: string, rollNumber: number) {
    this.name = name;
    this.rollNumber = rollNumber;
  }

  // Constructor with only name (roll number is optional)
  constructor(name: string) {
    this.name = name;
  }
}

// Create Student objects using different constructors
const studentWithRollNumber = new Student("Mateo Ishita", 11);
const studentWithoutRollNumber = new Student("Dvsch Gbjpiij");

// Access and print the properties
console.log("Student with Roll Number:");
console.log("Name:", studentWithRollNumber.name);
console.log("Roll Number:", studentWithRollNumber.rollNumber);

console.log("\nStudent without Roll Number:");
console.log("Name:", studentWithoutRollNumber.name);
console.log("Roll Number:", studentWithoutRollNumber.rollNumber); // This will be undefined

Explanations:

In the exercise above -

• First, we define the "Student" class with properties 'name' and 'rollNumber'.
• Next we provide two constructors for the "Student" class: one that takes both 'name' and 'rollNumber' as parameters and another that takes only 'name'. In the second constructor, we assume that 'rollNumber' is optional.
• Depending on which constructor is used, the 'rollNumber' property will either be initialized with the provided value or remain 'undefined'.
• Finally, we create two "Student" objects, one using each constructor, and access/print their properties to demonstrate constructor overloading.

Output:

"Student with Roll Number:"
"Name:"
"Mateo Ishita"
"Roll Number:"
11
"
Student without Roll Number:"
"Name:"
"Dvsch Gbjpiij"
"Roll Number:"
undefined

TypeScript Editor:

See the Pen TypeScript by w3resource (@w3resource) on CodePen.

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